nscale8x2_video()

LIB8STATIC void nscale8x2_video	(	uint8_t &	i,
		uint8_t &	j,
		fract8	scale )

Scale two one-byte values by a third one, which is treated as the numerator of a fraction whose demominator is 256.

In other words, it computes i,j * (scale / 256), ensuring that non-zero values passed in remain non zero, no matter how low the scale argument.

Warning

This function always modifies its arguments in place!

Parameters

i	first value to scale
j	second value to scale
scale	scale factor, in n/256 units

Definition at line 447 of file scale8.h.

                                                                      {
#if SCALE8_C == 1
    uint8_t nonzeroscale = (scale != 0) ? 1 : 0;
    i = (i == 0) ? 0 : (((int)i * (int)(scale)) >> 8) + nonzeroscale;
    j = (j == 0) ? 0 : (((int)j * (int)(scale)) >> 8) + nonzeroscale;
#elif SCALE8_AVRASM == 1
    nscale8_video_LEAVING_R1_DIRTY(i, scale);
    nscale8_video_LEAVING_R1_DIRTY(j, scale);
    cleanup_R1();
#else
#error "No implementation for nscale8x2 available."
#endif
}

References cleanup_R1(), LIB8STATIC, nscale8_video_LEAVING_R1_DIRTY(), and scale.

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